1. Technical Field
The present invention relates to a reflex-type screen and a screen apparatus. More specifically, the invention relates to a projection screen on which images are projected by a projector and the like, and a retractable projection screen apparatus.
2. Related Art
A reflex-type screen is conventionally used as a projection screen on which images are projected by a liquid crystal projector and the like. The screen reflects a light projected on the surface of the screen, and viewers observe the reflected light. Japanese Patent No. 3103802,for example, discloses a projection screen having an aluminum foil reflecting layer laminated onto a supporting material formed by a PET film, and a diffusing layer made of an OPP film laminated on the reflecting layer. Moreover, Japanese Patent Application Publication No. 2005-208558 describes a reflex-type screen having an aluminum foil reflecting layer provided on a PET film substrate, and a diffusing layer made of a transparent resin film laminated on the reflecting layer.
However, in the case of using these screens in a wind-up retractable screen apparatus, when the reflex-type screen is pulled out from the housing, the wound shape of the screen tends to remain and thus the flatness of the screen is impaired. Furthermore, at an edge of the reflex-type screen to which a winding shaft is jointed or secured, there occurs a step or level difference having a thickness of the screen edge. Therefore, when the reflex-type screen is tightly wound up, the screen is pressed against the step, which may leave a pressed mark on the screen surface. Because of the above-mentioned problems, the conventional reflex-type screens have a problem of unevenness in brightness when projecting an image light.
Another problem arises when the stiffness of the screen is increased in order to prevent the wound shape or the pressed mark of the screen. Increased stiffness requires higher torque for winding the screen, which means the screen has to be wound tightly with a strong force. Accordingly, the wound shape or the pressed mark cannot be prevented effectively. Meanwhile, when the stiffness of the screen is increased in order to reduce the wound shape or the pressed mark, the screen cannot be smoothly wound up. Although it may be effective to extend the external diameter of the winding shaft in order to solve the above-mentioned problem, another problem arises that the size of the screen apparatus becomes large.